41. A farmer wants apples that are crisper and more resistant to bruising. The farmer breeds apples with these target traits. After several generations, the farmer's orchards are producing apple crops with these traits. Which evolutionary mechanism is responsible for the changes in the gene pool of the farmer's crops?
Answer: B
Artificial selection is responsible for the changes in the gene pool of the farmer's crops.
The farmer's deliberate breeding of apples for specific traits, such as crispness and bruising resistance, exemplifies artificial selection. This process involves humans selecting which individuals to breed based on desired characteristics, leading to changes in the gene pool over generations.
A) Genetic drift
Genetic drift refers to random changes in allele frequencies within a population, often occurring in small populations. It is not applicable in this scenario, as the farmer's breeding efforts are intentional and target specific traits, rather than random fluctuations in genetics.
B) Artificial selection
Artificial selection is the correct mechanism in this case, as it involves human intervention to breed plants or animals for particular traits. The farmer's focus on producing crisper and more bruise-resistant apples clearly aligns with this process, as he selects specific individuals for breeding to achieve his goals.
C) Sexual selection
Sexual selection is a form of natural selection where certain traits increase an individual's chances of attracting mates. This mechanism does not apply to the situation described, as the farmer's goal is not related to mating preferences but rather focused on the agricultural traits of the apples themselves.
D) Gene flow
Gene flow involves the transfer of genetic material between populations, which can introduce new alleles into a gene pool. However, in this context, the farmer is not mixing different apple populations; instead, he is selectively breeding individuals within a single population to enhance specific traits, making gene flow irrelevant.
Conclusion
Artificial selection is the definitive mechanism at play in this scenario, as the farmer is intentionally breeding apples for specific characteristics. The other options—genetic drift, sexual selection, and gene flow—fail to explain the farmer's targeted approach to modifying the gene pool of his apple crops.